James Roosevelt graduated from Union College (NY) in 1847. He was an eligible bachelor: tall, slender, and wealthy, with considerable society connections. In 1853, he married his second cousin Rebecca Brien Howland (January 15, 1831 — August 21, 1876). They had one son, James Roosevelt "Rosey" Roosevelt.

Four years after Rebecca's death, he met a sixth cousin named Sara Ann Delano at a party celebrating graduation of his distant cousin Theodore Roosevelt, Jr. (1858–1919) from Harvard University. James and Sara were married on October 7, 1880 and became parents of Franklin Delano Roosevelt. He was reportedly a good father to Franklin; however, his recurring heart problems eventually turned him into an invalid. Franklin reacted by becoming fiercely protective of his father.

Roosevelt's business interests were primarily in coal and transportation. He was vice president of the Delaware and Hudson Railway, and president of the Southern Railway Security Company.

James died twenty years after he married Sara, and left the bulk of his estate to her, with only a modest inheritance for Franklin